Homoconjugated Acids as Low Cyclosiloxane-Producing Silanol Polycondensation Catalysts.

Polycondensation of α,ω-disilanols is a foundational technology for silicones producers. Commercially, this process is carried out with strong Brønsted acids and bases, which generates cyclosiloxane byproducts. Homoconjugated acids (a 2:1 complex of acid:base or a 1:1 complex of acid:salt), a seldom used class of silanol polycondensation catalysts, were evaluated for their ability to polymerize α,ω-disilanols while forming low levels of cyclosiloxane byproducts. Homoconjugated acid catalysts were highly active for silanol polycondensation, even when made from relatively mild acids such as acetic acid. Both the acid and base (or cation) component of the homoconjugated species was important for activity and avoiding cyclosiloxane byproduct formation. Stronger acids and bases were found to positively affect reactivity, and the pK a of the acid was found to correlate with cyclosiloxane byproduct formation. The individual components of the homoconjugated species (the acid and base) were ineffective as catalysts by themselves, and compositions with fewer than 2 mol of acid to 1 mol of base were much less reactive. Homoconjugated trifluoroacetic acid tetramethylguanidinium and tetrabutylphosphonium complexes were found to be privileged catalysts, able to give high-molecular-weight siloxanes (M n > 60 kDa) while generating less than 100 ppm of octamethylcyclotetrasiloxane byproduct. Finally, a mechanism has been proposed where silanols are electrophilically and nucleophilically activated by the homoconjugated species, leading to silanol polycondensation.

Computational and Experimental Studies of Regioselective SNAr Halide Exchange (Halex) Reactions of Pentachloropyridine.

The Halex reaction of pentachloropyridine with fluoride ion was studied experimentally and computationally with a modified ab initio G3MP2B3 method. The G3 procedure was altered, as the anionic transition state optimizations failed due to the lack of diffuse functions in the small 6-31G* basis set. Experimental Halex regioselectivities were consistent with kinetic control at the 4-position. The reverse Halex reaction of fluoropyridines with chloride sources was demonstrated using precipitation of LiF in DMSO as a driving force. Reverse Halex regioselectivity at the 4-position was predicted by computations and was consistent with kinetic control. Scrambling of halide ions between chlorofluoropyridines was catalyzed by n-Bu4PCl, and the products of these reactions were shown to result from a combination of kinetic and thermodynamic control. Comparison of the C-F and C-Cl homolytic bond dissociation energies suggests that an important thermodynamic factor which controls regioselectivity in this system is the weak C2-Cl bond. The differences between ΔH° values of chlorofluoropyridines can be explained by a combination of three factors: (1) the number of fluorine atoms in the molecule, (2) the number of fluorine atoms at the C2 and C6 positions, and (3) the number of pairs of fluorine atoms which are ortho to one another.

A safety culture transformation: its effects at a children's hospital.

OBJECTIVE: To improve pediatric patient safety at a tertiary, 200-bed children's hospital by changing the safety culture and implementing processes, practices, and measures to sustain improvements. Although many core quality and safety measures exist for adult acute-care facilities, equivalent measures for pediatrics are lacking. METHODS: Helen DeVos Children's Hospital in Grand Rapids, Michigan, part of the Spectrum Health system, led a 2-year initiative beginning in late 2007 to improve pediatric patient safety. Key strategies included safety-based staff training, training in root cause analysis, failure mode classification of events and safety behavior, integration of and collaboration between risk management and clinical staff, consistent coding and classification of serious safety events and adoption of multiple safety metrics, creating a new safety leadership infrastructure, and fostering transparency of data and safety event details. RESULTS: The 2-year initiative led to an estimated 68% decrease in the number of serious safety events and adoption of a serious safety event metric reported monthly. In addition, compliance with the ventilator-associated pneumonia bundle rose from 2% to 96%; hand hygiene compliance rates rose from 56% to 95%; and the Children's Asthma Care-3 core measure, home management plan of care given to patient/caregiver, rose from 0% to 83% within 6 months. Medication errors with serious harm were reduced to only two during the initiative, and ventilator-associated pneumonias dramatically decreased, with only one occurring in 2009. CONCLUSIONS: The initiative led to key improvements in safety culture and patient safety and also had a broad impact on several clinical quality outcome measures. Using safety metrics improves transparency and enables future benchmarking with peer institutions to help improve pediatric patient safety nationwide. Because of the initiative's success in our children's hospital, the entire Spectrum Health system, including more than 16,000 staff members, is now undertaking a similar effort.

One-pot synthesis of Mo(0) dinitrogen complexes possessing monodentate and multidentate phosphine ligands.

Mo(0) dinitrogen complexes bearing electron-rich mono- and bidentate phosphines can be synthesized in good yields from inexpensive and readily accessible MoCl(5) via a one-step mild reduction with Mg metal. trans-[(N(2))(2)Mo(PMePh(2))(PPh(CH(2)CH(2)PPh(2))(2))] can also be obtained via this strategy. However, in the presence of tri- and tetradentate ligands that are sterically restrictive, the analogous reduction leads to either (η(6)-arene) formation or [Mo(multidentate phosphine)(m)](n) oligomer complexes that have no dinitrogen ligands. One such η(6)-arene complex, where the Mo(0) center is ligated by 1,1,1-tris(diphenylphosphinomethyl)ethane, was isolated and characterized via X-ray crystallography.

Insurance-associated disparities in hospitalization outcomes of Michigan children.

OBJECTIVE: To investigate whether children in Michigan with private insurance have better hospitalization-related outcomes than those with public or no insurance. STUDY DESIGN: Population-based hospitalization rates were calculated for newborns and children aged <18 years in Michigan for the years 2001-2006 and stratified by age, disease grouping, and health insurance status using inpatient records from the Michigan Inpatient Database and population estimates from the US Census Current Population Survey. RESULTS: Michigan children with public/no insurance had significantly higher overall hospital admission rates and admission rates for ambulatory-sensitive conditions, and were more likely to be admitted through the emergency room, compared with those with private health insurance. Similarly, newborns with public/no insurance had significantly higher rates of hospitalization-related outcomes. Hospital charges per child were higher in the public/no insurance population, translating to potential excess charges of between $309.8 and $401.8 million in 2006. CONCLUSIONS: There are disparities in health outcomes and charges between Michigan children and newborns with public/no insurance and those with private health insurance, presenting a significant opportunity to improve the efficiency and efficacy of care.